Manufacture of rubber vulcanizates containing filler and polyethylene glycol ethers



Patented Jan. 8, 1957 Free MANUFACTURE OF RUBBER VULCANIZATES CONTAINING FILLER AND POLYETHYLENE GLYCOL ETHERS Rudolf Kern, Neustadt (Haardt), and Willy Lautsch, Berlin-Dahlem, Germany, assignors to Rhein-Chemie G. m. b. H., Heidelberg, Germany, a corporation of Germany No Drawing. Application June 13, 1951, Serial No. 231,426

Claims. (Cl. 260-761) This invention relates to a process for the manufacture of rubber vulcanizates.

The primary object of our invention is to generally improve the vulcanizates referred to, and other objects of this invention will become apparent from the following description.

According to our present invention, we use non-ionic agents to be added to rubber or vulcanizable synthetic plastic compositions. Our addition agents bear at least one hydrophobic radical R1, and at least one hydrophilic radical R2 and/or at least one hydrophobic radical R3, R2 and/or R3 being linked to R1 over an oxygen atom. The oxygen atom may originate, for instance, from a hydroxyl, carboxyl or sulfonic group.

Examples of the hydrophobic radical R1 are a normal, iso-alkyl, alkylphenyl, monoalkyl or polyalkyl aromatic hydrocarbon radical, and their hydrogenated derivatives, such as resin alcohols. If R1 is of an aliphatic structure, it may consist of a fatty acid radical of natural saturated or unsaturated fatty acids, of fatty acids obtained by oxidation ofparaffin, or of the corresponding alcohols.

The hy-drophilic radical R2 may be formed by polyglycol ether radicals, monoxy alcohols or polyoxy alcohols, such, as, for example, polyvinyl alcohol radicals and sugar alcohol radicals.

The hydrophobic radical R3 derives from aliphatic or aromatic alcohols of any chain length.

The addition agents of our invention may have the structure of esters or ethers when the hydrophobic radical R1 is linked to the hydrophilic radical R2 by means of an oxygen bridge.

Among the addition agents suitable for the process of this invention, the following compounds were found to be particularly advantageous, but it is to be understood that these are enumerated as examples only without limiting the invention to these examples:

Polyglycol esters of fatty acids, resin acids, naphthenic acids, or of acids obtained by oxidation of paraffin; psolyglycol ethers of fatty alcohols, alkyl phenols or naphthols; esters of aromatic sulfonic acids formed with monovalent polymolecular alcohols; butyl, isooctyl or other alcohol esters of the above mentioned carboxylic or sulfonic acids; fatty acid monoglycerides; esters of the above mentioned carboxylic and sulfonic acids with polyalcohols, such as pentaerythritite, sugar alcohols, polyvinyl alcohols, etc.

Our addition agents bring about a substantial improvement of the mechanical properties, especially as far as tensile strength and tear and cut growth resistance of synthetic plastic and rubber compositions are concerned.

This is particularly true in the case of compositions con taining white or light-colored fillers, such as magnesium oxide, alumina gel, kieselguhr, siliceous chalk, silica gel, calcium silicate, aluminum silicate, active zinc oxide. etc., and mixtures of these fillers with each other and with other fillers, such as carbon black.

The non-ionic agents of our invention when added to rubber or plastic compositions have a strong dispersing action on the fillers which facilitates mixing and, therefore, reduces the amount of energy necessary in the masticating or milling operation.

The working of the rubber or synthetic plastic compositions is further facilitated by adding our addition agents together with water. The water may be added either as such or in form of aqueous solutions or emulsions of the addition agents.

The presence of water, even with higher filler contents, produces, a transparency which reaches a maximum at a water concentration which depends on the formulation of the composition and especially the kind and quantity of the filler used.

The non-ionic agents of the invention may also be used in mixtures with each other or in combination with other dispersing agents or other auxiliary materials, softeners, etc.

The quantity of the non-ionic agents to be added to the rubber or plastic compositions according to the process of our invention varies within wide limits. It will depend on the kind and composition of the agent, for instance, the degree of oxyethylation, as well as the kind, quantity and hydrophilic properties of the tiller which is to be added to the rubber or synthetic plastic composition. It will further depend on the desired physical or technical properties of the rubber vulcanizate or synthetic plastic composition to be prepared with the addition of the min ionic agents. It is preferable to select the addition agents in accordance with the filler used and to add the addition agents in a quantity which will impart optimum properties to the synthetic plastic material or rubber vulcanizate.

From the examples given below it will be seen that the addition agents in many cases multiply the mechanical strength ascertained in parallel experiments not using the addition agents of the invention. It will be clear that the following examples are intended to illustrate the method of the invention but do not limit its scope.

Example 1 A rubber compound was made up from:

The addition agent was produced by reacting one moi of abietic acid with six m-ols of ethylene oxide.

After vulcanization at 45 p. s. i. gauge pressure for 45 minutes, the vulcanizate showed the following test results, as compared with those of a vulcanizate prepared without the addition agent:

Tensile strength, kg./sq. cm 146 118 Elongation, percent 503 173 Youngs modulus at:

300%, kg./sq. cm 61 55 500%, kg./sq. cm 146 Tear resistance, kg/cm. 16 5. 5 Cut; growth resistance, k ./c 40 23 Shore hardness 55 55 Shock elasticity, percent 63 65 Example 2 A rubber compound was prepared from: Crepe rubber 100 Zinc oxide, active 3 Sulfur 3 Mercaptobenzothiazole 'disulfide 1 Dipheny'l-guanidine 0.5 Alumina gel 60 Hexylheptyl naphthol polyglycol ether with 8 mols ethylene oxide 3.6

After vulcanization at 45 p. s. i. gauge pressure for 10 minutes, the following test results were obtained, as compared with those of a vulcanizate of the same composition but notcontaining the addition agent:

Butylphenol-polyglycol ether synthetized by oxyethylation of 1 mol butylphenol with 10-l5 mols of ethylene oxide 3.6

After vulcanization for 10 minutes at 45 p. s. i. gauge pressure, the following testresults were-obtained, as cornparedwith those of a-vulcanizate-not containing the addition agent:

Tensile strength, kg./sq. cm 160 115 Elongation, percent 500 440 Young's modulus at:

300%, kgJsq. cm. 64 56 500%, lrg./sq. cm... 157 Tear resistance, kgJcm. 16 3 Cut growth resistance, kgJern. 47 17 Shore hardness 5G 55 Shock elasticity, percent compared with those given by a vulcanizate prepared without the addition agent:

Elongation, percent 443 463 Young's modulus at 300%, kg./sq. cm A. 68 59 Tour resistance, kgJcm l6 5. 8 Cut growth resistance, kg/enL. 39 22 Shore hardness 58 56 Shoe]: elastieityypereent 68 05 Example 5 A rubber compound was prepared consistingof:

Crepe rubber 100 Zinc oxide, active 3 Sulfur 3 Mercaptobenzothiazole disulfide 1 Diphenyl-guanidine 0.5 Alumina gel 60 Butylphenol-polyglycol ether made by oxyethylation of 1 mol butylphen-ol with 6-7 mols ethylene oxide 3 .6

After "vulcanization at 45 p. s. i. gauge pressure for 20 minutes, the following test results were obtained, as compared with those .given by a vulcanizate not containing the addition agent:

Tensile strength, ken/sq. cm 155 121 Elongation, percent 497 453 Young's modulus at 300%, l 63 63 'lear resistance, ken/cm 8. 4 5. 5 Out growth resistance, kg./c1n 40 22 Shore hardness 55 55 Shook elasticity, percent 03 till Example 6 A rubber compound was prepared from:

Crepe rubber 100 Zinc .oxide, active 3 Sulfur 3 lvlercaptobenzothiazole disulfide l Diphenyleguanidine 0.5 Alumina gel 6 Parafiin'fatty alcohol polyglycol ether with 20'mols ethylene oxide synthetized by reacting the fatty alcohols obtained by reduction of fatty acids produced by.oxidation :of parafiin, and containing 15-20 carbon atoms per molecule, with '20 mols ethylene oxide 3.6

After vulcanizationat p. s. i. gauge pressure for 30 minutes, thefollowing test results were obtained, compared with those of a vulcanizate produced without the addition agent:

In the Examples 4 and 5 below, the influence of the degree of the oxyethylation -of butylphenol-polyglycolether on the properties of a rubber vulcanizate prepared with this addition agent is illustrated.

Example 4 A rubber compound was prepared from:

Butylphenol-polyg-lycol ether made by oxyethylation of 1 mol butylphenol with 4-5 -inols ethylene oxide 3.6

The following test results were obtained after vulcanization at 45 p. s. i. gauge pressurefor 30 minutes, as

Tensile strength, kg./sq. crn 135 121 Elongation, percent 503 M3 Young's modulus at:

300 kgJsq. em 56 5'.) a 500 kg./sq. 132 'l ear resistance, kg./c1:n 14 g 5. 8 Cut growth resistance, kg/enL. 35 ,2: Shore hardness c c i 57 56 Shock elasticity, percent G6 05 Similar results can be obtained by using the correspondmg fatty acid polyglycol ester.

Example 7 A rubbercornpound was prepared from:

Crepe rubber Zinc oxide, active 3 Sulfur 3 M ercaptobenzot-hiazole disulfidc 1 Diphenylguanidine "0.5 Alumina gel 60 Toluenesulfonic acid dodecyl ester 3.6

After vulcanization at 45 p. s. i. gaugepressure for 10 minutes, the following test results were obtained, as

compared with those of a vulcanizate prepared without the toluenesulfonic acid ester:

Tensile strength, kg./sq. cm Elongation, percent Youngs modulus at:

300%. kg./sq. cm 78 70 500%, kg./sq. sm 185 174 Tear resistance, kg./em. 20 17 Cut growth resistance, k cm 09 43 Shore hardness 58 55 Shock elasticity, percent" 67 63 Example 8 This example illustrates the further improvement in mechanical properties of a rubber vulcanizate brought out by adding water to toluenesulfonic acid paraffin fatty alcohol ester when used as a dispersing agent. The formulation consisted of Crepe rubber 1 100 Zinc oxide, active 3 Sulfur 3 -lVlercaptobenzothiazole disulfide 1 Diphenyl-guanidine Alumina gel Vulcanizates were prepared at 45 p. s. i. gauge pressure in 10 minutes from the basic mixture (A); from the same mixture with the addition of 3.6 parts of toluenesulfonic acid parafi'in fatty alcohol ester (B); and from the same mixture with the addition of 3.6 parts of an emulsion of toluenesulfonic acid parafiin fatty alcohol ester with 10% water (C). As to these three vulcanizates, the following test results were obtained:

A. B O

Tensile strength, kg./sq. cm i 187 228. 219 Elongation, percent 527 563 500 Young's modulus:

300%, kg./sq. cm 70 75 76 500%, kg./st1. cm... 174 189 180 Tear strength, kgJcm 17 28 31 Cut growth resistance, k /cm 43 58 07 Shore hardness t 55 56 56 Shock elasticity, percent... 63 66 64 Example 9 From this example it will be seen that an appreciable improvement in the mechanical properties of rubber vulcanizates can be achieved even with the use of a 30% solution of the oxyethylation product of isooctylphenol. The formulation used consisted of:

After vulcanization at 45 p. s. i. gauge pressure for 10 minutes, the vulcanizate had the following physical properties, as compared with those of a vulcamzate pre pared without the addition agent:

Tensile strength, kgJsq. cm 219 187 Elongation, percent 570 527 Youngs modulus:

300%, kg./sq. cm 66 70 kgJsq. cm 167 174 Tear resistance, kg. cm 43 17 Out growth resistance, kg./cm 53 43 Shore hardness 55 Shock elasticity, percent 60 63 Example 10 This example illustrates the influence of the degree of awzoos oxyethylation of an oxyethylated technical grade of laurylalcohol, which is used as a dispersing agent, on the physical properties of a rubber vulcanizate. A rubber compound was prepared from:

Crepe rubber Zinc oxide, active 1- 3 Sulfur 3 lvlercaptobenzothiazole disulfide l Diphenyl-guanidine 0.5 Alumina gel 60 To the basic composition (A) were added, respectively, 3.6 parts of:

1 (B) Lauryl alcohol, oxyethylated with 6 mols of ethylene oxide, C2H4O (C) Lauryl alcohol, oxyethylated with 12 mols CzHiO (D) Lauryl alcohol, oxyethylated with 18 mols C2H4O (E) Lauryl alcohol, oxyethylated with 24 mols C2H4O The same technical grade of lauryl alcohol was used in all four cases. After vulcanization at 45 p. s. i. gauge pressure for 60 minutes, the following physical properties of A to E were determined by test:

Tensile strength, kg./sq. cm 203 198 217 207 Elongation, percent 577 547 550 580 553 Youngs modulus:

300%, kg./s emu" 56 71 70 71 78 500%, kgJsq. cm. 132 175 167 107 175 Tear resistance, kgJc 11 35 38 42 4 3 Cut growth resistanee,l Shore hardness 56 60 61 (i3 62 Shoclr elasticity, percent 57 54 52 50 51 Example 11 This example illustrates the influence of a paraflin fatty alcohol, oxyethylated with 25 mols of ethylene oxide, on the mechanical properties of a rubber vulcanizate. The compound was made-up from:

After vulcanization at 45 p. s. i. gauge pressure for 60 minutes, the vulcanizate gave the following test results, as compared with those of a vulcanizate prepared without the addition agent:

Tensile strength, kg./sq. cm Elongation, percent 607 577 Youngs modulus at:

300%, kg./sq. 0111.. 34 50 500%, kg./sq. em 132 132 Tear resistance, kg./cm 38 11 Cut growth resistance, kg./cm.1 57 58 Shore hardness 55 5? Shock elasticity, percent 52 57 Example 12 This example shows that the dispersing agent of Example 11 improves the physical properties of a rubber vulcanizate even when used in form of a 10% aqueous emulsion. The following formulation was used:

Crepe rubber 100 Zinc oxide, active 3 Sulfur 3 Mercaptobenzothiazole disulfide 1 Diphenyl-guanidine 0.5 Aluminum gel 60 Parafiin fatty alcohol, oxyethylated with 25 mols ethylene oxide, in 10% emulsion 3.6

After vulcanization at 45 p. s. i. gauge pressure for 20 minutes, the following test results were obtained, as compared with those of a vulcanizate prepared without the addition agent:

Tensile strength, kg/squcm Elongation, percent Youngs modulus at:

300%, kg/sq. cm 75 08 500%, kg/sq. ems... l 107 Tear resistance, kgJcin l .r 18 16 Cut growth resistance, kgJem 54 50 Shore hardness 58 55 Shock elasticity, percent 64 62 Example 13 Crepe rubber 100 Zinc oxide, active 3 Sulfur 3 Mercaptobenzothiazole disulfidc l Diphenyl-guanidine 0.5 Aluminum silicate 60 Identical compositions were prepared except for the addition of, respectively, (B) 3.6 parts of lauryl-polyglycol ether (degree of polymerization 24) and (C) 10 parts of laurylpolyglycol ether. After curing at 45 p. s. i. gauge pressure for 20 minutes, the following test data were obtained with the three vulcanizates:

A B O Tensile strength, kgJsq. cm G6 75 170 Elongation, percent 360 320 490 Youngsniodulus nt 300%, kg/sq. crn 52 (54 80 Teal resistancc. lie/cm 3. 7 4 27 Cut growth resistance, kgn/crnx 12 14 40 Shore hardness 52 58 Shock elasticity, percent 50 48 48 With a lauryl-polyglycol ether content of 3.6% relative to rubber, no significant improvement of the mechanical properties, especially tear resistance, occurs. With a higher proportion of the dispersing agent in the same test composition, the tear resistance was improved about sevenfold, as compared to the tear resistance of the composition containing no dispersing agent. The tensile strength was doubled, and the out growth resistance was increased in a similar proportion.

Example 14 This example shows the substantial improvement in mechanical properties achieved with calcium silicate as a filler when used with the addition agents of the invention. The following formulation was used:

Crepe rubber 100 Zinc oxide, active 3 Sulfur 3 Mercaptobenzothiazolc disulfide 1 Diphenyl-guanidine 0.5 Calcium silicate 6O Lauryl-polyglycol ether (degree of polymerization 24) After vulcanization at 45 p. s. i. gauge pressure for 10 minutes, the vulcanizate had the following physical properties, as compared to those of a vulcanizate prepared without the lauryl-polyglycol ether:

Due to the addition of the dispersing agent, the tear strength is increased in this instance twelvefold. The tensile strength is tripled, and the cut growth resistance is increased six times.

Example 15 This example demonstrates the improvement in tear resistance and in physical characteristics ,of a rubber composition containing a pyrogen silica filler when laurylpolyglycol ether of a degree of polymerization of 18 is added. The following formulation was used:

Crepe rubber Zinc oxide, active 3 Sulfur 3 Mercaptobenzothiazole disulfide 1 Diphenyl-guanidine 0.5 Pyrogen silica 75 Lauryl-polyglycol ether (degree of polymerization After vulcanization at 45 p. s. i. gauge pressure for 60 minutes, the following test results were obtained, as compared with those given by the same composition but without the dispersing agent:

Tensile strength, kg./sq. cnr. Elongation, percent Young's modulus at:

300%, kg./sq. em 500%, kg./sq. emu." Tear resistance, kgJcm Out growth resistance, kg./en1 Shore hardness l. Shock elasticity, percent The vulcanizate prepared without the dispersing agent had the characteristics of tough leather or of a wooden board. Only the vulcanizate made with addition of the dispersing agent had rubberlike characteristics.

It will be apparent that While We have described our invention in preferred forms, many changes and modifications may be made without departing from the spirit of the invention defined in the following claims.

We claim:

1. In the process according to claim 5, admixing parafiin fatty alcohol-polyethylene glycol ethers to serve as said polyethylene glycol ethers of aliphatic alcohols, the former being obtained by reduction of fatty acids produced by oxidation of paraffin, and containing 15 to 20 carbon atoms per molecule.

2. In the process according to claim 5, admixing polyethylene glycol ethers of lauryl alcohol to serve as said polyethylene glycol ethers of aliphatic alcohols.

3. In the process according to claim 5, admixing butylphenol-polyethylene glycol ethers to serve as said polyethylene glycol ethers of alkylated phenols.

4. In the process according to claim 3, admixing butylphenol-polyethylene glycol ethers syntheti'zed by oxycthylation of 1 mol butylphenol with a multiple number of mols of ethylene oxide.

5. Process for the manufacturing of rubber vulcanizates, comprising compounding natural rubber, light-colored hydrophilic fillers, and addition agents selected from the group consisting of polyethylene glycol ethers of aliphatic inonohydric alcohols having 12 to 20 carbon atoms, polyethylene glycol ethers of alkylated phenols, hexylheptyl-naphthol-polyethylene glycol ethers, and mixtures 2,099,651 Helft Nov. 16, 1937 10 Graves May 24, 1938 Smith Feb. 29, 1944 Novotny et a1 July 25, 1944 Sarbach Oct. 24, 1944 Tann Aug. 7, 1945 Zwicker Oct. 16, 1945 Vesce Apr. 22, 1947 

5. PROCESS FOR THE MANUFACTURING OF RUBBER VULCANIZATES, COMPRISING COMPOUNDING NATURAL RUBBER, LIGHT-COLORED HYDROPHILIC FILLERS, AND ADDITION AGENTS SELECTED FROM THE GROUP CONSISTING OF POLYETHYLENE GLYCOL ETHERS OF ALIPHATIC MONOHYDRIC ALCOHOLS HAVING 12 TO 20 CARBON ATOMS, POLYETHYLENE GLYCOL ETHERS OF ALKYLATED PHENOLS, HEXYLHEPTYL-NAPHTHOL-POLYETHYLENE GLYCOL ETHERS, AND MIXTURES THEREOF, SAID LIGHT-COLORED HYDROPHILIC FIBERS BEING SELECTED FROM THE GROUP CONSISTING OF ALUMINA GEL, ALUMINUM SILICATE, CALCIUM SILICATE, PYROGENIC SILICA, AND MIXTURES THEREOF. 